In the field of this disclosure, it is common to use a color difference metric to measure the “color difference” or “color movement” between an original color and a mapped color. For example, a commonly used metric is the deltaE color difference metric, which is evaluated in the Lab 3-D color space. The deltaE metric is the magnitude of the 3-D color distance between the original color and the mapped color (in the 3-D color space).
Given an original color (L1, a1, b1) and a mapped color (L2, a2, b2), the deltaE color distance is the Euclidean distance, or the straight line distance between the two color points in Lab space, as represented by Equation 1:deltaE=√{square root over ((L1−L2)2+(a1−a2)2+(b1−b2)2)}{square root over ((L1−L2)2+(a1−a2)2+(b1−b2)2)}{square root over ((L1−L2)2+(a1−a2)2+(b1−b2)2)}  (Equation 1)
Thus, the deltaE metric represents the magnitude of the 3-D color distance between the original color and the mapped color.